The mighty option parser used by yargs.
visit the yargs website for more examples, and thorough usage instructions.
npm i yargs-parser --save
var argv = require('yargs-parser')(process.argv.slice(2)) console.log(argv)
node example.js --foo=33 --bar hello { _: [], foo: 33, bar: 'hello' }
or parse a string!
var argv = require('yargs-parser')('--foo=99 --bar=33') console.log(argv)
{ _: [], foo: 99, bar: 33 }
Convert an array of mixed types before passing to yargs-parser
:
var parse = require('yargs-parser') parse(['-f', 11, '--zoom', 55].join(' ')) // <-- array to string parse(['-f', 11, '--zoom', 55].map(String)) // <-- array of strings
Parses command line arguments returning a simple mapping of keys and values.
expects:
args
: a string or array of strings representing the options to parse.opts
: provide a set of hints indicating how args
should be parsed:opts.alias
: an object representing the set of aliases for a key: {alias: {foo: ['f']}}
.opts.array
: indicate that keys should be parsed as an array: {array: ['foo', 'bar']}
.{array: [{ key: 'foo', boolean: true }, {key: 'bar', number: true}]}
.opts.boolean
: arguments should be parsed as booleans: {boolean: ['x', 'y']}
.opts.coerce
: provide a custom synchronous function that returns a coerced value from the argument provided (or throws an error). For arrays the function is called only once for the entire array:{coerce: {foo: function (arg) {return modifiedArg}}}
.opts.config
: indicate a key that represents a path to a configuration file (this file will be loaded and parsed).opts.configObjects
: configuration objects to parse, their properties will be set as arguments:{configObjects: [{'x': 5, 'y': 33}, {'z': 44}]}
.opts.configuration
: provide configuration options to the yargs-parser (see: configuration).opts.count
: indicate a key that should be used as a counter, e.g., -vvv
= {v: 3}
.opts.default
: provide default values for keys: {default: {x: 33, y: 'hello world!'}}
.opts.envPrefix
: environment variables (process.env
) with the prefix provided should be parsed.opts.narg
: specify that a key requires n
arguments: {narg: {x: 2}}
.opts.normalize
: path.normalize()
will be applied to values set to this key.opts.number
: keys should be treated as numbers.opts.string
: keys should be treated as strings (even if they resemble a number -x 33
).returns:
obj
: an object representing the parsed value of args
key/value
: key value pairs for each argument and their aliases._
: an array representing the positional arguments.--
: an array with arguments after the end-of-options flag --
.Parses a command line string, returning detailed information required by the yargs engine.
expects:
args
: a string or array of strings representing options to parse.opts
: provide a set of hints indicating how args
, inputs are identical to require('yargs-parser')(args, opts={})
.returns:
argv
: an object representing the parsed value of args
key/value
: key value pairs for each argument and their aliases._
: an array representing the positional arguments.--
: an array with arguments after the end-of-options flag --
.error
: populated with an error object if an exception occurred during parsing.aliases
: the inferred list of aliases built by combining lists in opts.alias
.newAliases
: any new aliases added via camel-case expansion:boolean
: { fooBar: true }
defaulted
: any new argument created by opts.default
, no aliases included.boolean
: { foo: true }
configuration
: given by default settings and opts.configuration
.The yargs-parser applies several automated transformations on the keys provided in args
. These features can be turned on and off using the configuration
field of opts
.
var parsed = parser(['--no-dice'], { configuration: { 'boolean-negation': false } })
true
.short-option-groups
.Should a group of short-options be treated as boolean flags?
node example.js -abc { _: [], a: true, b: true, c: true }
if disabled:
node example.js -abc { _: [], abc: true }
true
.camel-case-expansion
.Should hyphenated arguments be expanded into camel-case aliases?
node example.js --foo-bar { _: [], 'foo-bar': true, fooBar: true }
if disabled:
node example.js --foo-bar { _: [], 'foo-bar': true }
true
dot-notation
Should keys that contain .
be treated as objects?
node example.js --foo.bar { _: [], foo: { bar: true } }
if disabled:
node example.js --foo.bar { _: [], "foo.bar": true }
true
parse-numbers
Should keys that look like numbers be treated as such?
node example.js --foo=99.3 { _: [], foo: 99.3 }
if disabled:
node example.js --foo=99.3 { _: [], foo: "99.3" }
true
boolean-negation
Should variables prefixed with --no
be treated as negations?
node example.js --no-foo { _: [], foo: false }
if disabled:
node example.js --no-foo { _: [], "no-foo": true }
false
combine-arrays
Should arrays be combined when provided by both command line arguments and a configuration file.
true
duplicate-arguments-array
Should arguments be coerced into an array when duplicated:
node example.js -x 1 -x 2 { _: [], x: [1, 2] }
if disabled:
node example.js -x 1 -x 2 { _: [], x: 2 }
true
flatten-duplicate-arrays
Should array arguments be coerced into a single array when duplicated:
node example.js -x 1 2 -x 3 4 { _: [], x: [1, 2, 3, 4] }
if disabled:
node example.js -x 1 2 -x 3 4 { _: [], x: [[1, 2], [3, 4]] }
no-
negation-prefix
The prefix to use for negated boolean variables.
node example.js --no-foo { _: [], foo: false }
if set to quux
:
node example.js --quuxfoo { _: [], foo: false }
false
.populate--
Should unparsed flags be stored in --
or _
.
If disabled:
node example.js a -b -- x y { _: [ 'a', 'x', 'y' ], b: true }
If enabled:
node example.js a -b -- x y { _: [ 'a' ], '--': [ 'x', 'y' ], b: true }
false
.set-placeholder-key
.Should a placeholder be added for keys not set via the corresponding CLI argument?
If disabled:
node example.js -a 1 -c 2 { _: [], a: 1, c: 2 }
If enabled:
node example.js -a 1 -c 2 { _: [], a: 1, b: undefined, c: 2 }
false
.halt-at-non-option
.Should parsing stop at the first positional argument? This is similar to how e.g. ssh
parses its command line.
If disabled:
node example.js -a run b -x y { _: [ 'b' ], a: 'run', x: 'y' }
If enabled:
node example.js -a run b -x y { _: [ 'b', '-x', 'y' ], a: 'run' }
false
strip-aliased
Should aliases be removed before returning results?
If disabled:
node example.js --test-field 1 { _: [], 'test-field': 1, testField: 1, 'test-alias': 1, testAlias: 1 }
If enabled:
node example.js --test-field 1 { _: [], 'test-field': 1, testField: 1 }
false
strip-dashed
Should dashed keys be removed before returning results? This option has no effect if camel-case-expansion
is disabled.
If disabled:
node example.js --test-field 1 { _: [], 'test-field': 1, testField: 1 }
If enabled:
node example.js --test-field 1 { _: [], testField: 1 }
false
unknown-options-as-args
Should unknown options be treated like regular arguments? An unknown option is one that is not configured in opts
.
If disabled
node example.js --unknown-option --known-option 2 --string-option --unknown-option2 { _: [], unknownOption: true, knownOption: 2, stringOption: '', unknownOption2: true }
If enabled
node example.js --unknown-option --known-option 2 --string-option --unknown-option2 { _: ['--unknown-option'], knownOption: 2, stringOption: '--unknown-option2' }
The yargs project evolves from optimist and minimist. It owes its existence to a lot of James Halliday's hard work. Thanks substack beep boop \o/
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